644306401 has 2 divisors, whose sum is σ = 644306402. Its totient is φ = 644306400.

The previous prime is 644306363. The next prime is 644306423. The reversal of 644306401 is 104603446.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 589324176 + 54982225 = 24276^2 + 7415^2 .

It is a cyclic number.

It is not a de Polignac number, because 644306401 - 2⁹ = 644305889 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644306401.

It is not a weakly prime, because it can be changed into another prime (644306441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322153200 + 322153201.

It is an arithmetic number, because the mean of its divisors is an integer number (322153201).

Almost surely, 2^644306401 is an apocalyptic number.

It is an amenable number.

644306401 is a deficient number, since it is larger than the sum of its proper divisors (1).

644306401 is an equidigital number, since it uses as much as digits as its factorization.

644306401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 28.

The square root of 644306401 is about 25383.1913084230. The cubic root of 644306401 is about 863.7024442784.

Adding to 644306401 its reverse (104603446), we get a palindrome (748909847).

The spelling of 644306401 in words is "six hundred forty-four million, three hundred six thousand, four hundred one".